We got a call a few weeks before the 2018 SCCA Solo Nationals from a racer who had just bought a 2016 Audi TT. He wanted to campaign the car in the new STH autocross class - the Street Touring class for the "Hot" hatch turbo cars. He thought it might have a good shot in this class with the right suspension and power upgrades. He had a very short time frame but he made the right calls and enlisted Vorshlag to get him the right suspension. This was our first Mk3 Audi TT install so we wrote this post to cover our research, calculations, and installation.

PICKING THE RIGHT SUSPENSION OPTION

When it comes to late model German sports cars we have a number of options available - Bilstein (BTS, PSS10, Club Sport), Ohlins (R&T + Motorsport options) and MCS (TT1, TT2, RR2, and RR3). There are a lot of variables that go into these choices, including availability/time frame, number of adjustments, street vs motorsport use, and of course cost.

After talking to the TT owner, Thomas, about his experience, skills, class limits, needs, and target (National Championship!) Jason helped him hone in on these MCS RR2 - remote reservoir double adjustable monotube coilovers. This is the best shock we commonly sell but we typically only recommend them for folks building for serious competition. This is not what you want for your daily driver, but if you are chasing hundredths of a second and need a lot of spring rate, these cannot be beat. After speaking with MCS and telling them about the super tight timeline they made it happen and shipped the shocks in less than a week.

From conversations we had with the guys at MCS we knew the Mk7 Golf GTI shared the same suspension as this Audi, so our Mk7 GTI camber/caster plates could be adapted. We did some calculations spring rate based off of the data we had from similar cars and came up with a spring package using Hyperco springs using a 600 #/in front rate and 900 #/in rear.

TACKLING A CHALLENGING INSTALL

Once the car was here we already had the springs, MCS shocks, Vorshlag camber plates and some other items handy. Now "all we had to do" was put everything on and make it work. We had 3 days.

The rear suspension is a multi-link design with an inboard mounted (divorced) spring that sits on top of a control arm and nests onto a nipple on the chassis. Due to space constraints for the rear tire we had to keep the MCS setup with this divorced rear spring mounting instead of going to a coilover rear (which could make even the 245mm tire not fit). As you can see above we have a Hyperco coilover spring mounted in that inboard location. This gives the spring there a motion ratio of about "half" so the wheel rate of the spring is about half that of the 900#/in rating.

Thomas drove up to our shop from 4 hours away to drop off the car and we got to work. We measured stock ride heights, total droop, toe and camber at each corner. This car only started with -1.0° front camber but it had -1.9° rear, so that end was in good shape at least.

The front strut install was straightforward, except for the hose routing for the remote canisters - which was blocked by many things under hood. Then there was the strut tower, which was very confining...

This was our main challenge - the strut stem and the protruding Rebound knob would be confined within the tiny opening of the tower, massively limiting camber travel. This is a problem that is all too common on modern VW/Audi cars. So we did some tricks to lower the top of the strut shaft so that it could slide under the lip of the strut tower protrusion. If we could trim the towers it would have been possible to keep the knobs on, but as it is an 8mm wrench can be used adjust the Rebound up front. What Jason came up with was stacking 3 additional "top pointer rings" onto each side to position the shaft just under the lip of the tower. Without this change we wouldn't have gotten more than -1.5° front camber, but like this we were able to get -2.8° camber with no cutting.

Out back the only challenge was machining a custom Delrin adapter to work with an adjustable ride height platform we machine in house and use on various BMW and Mustang "divorced spring setups like this. The ride height adjuster fits into this adapter that was machined to fit over the nipple on the chassis, as shown below. The 60mm ID spring fit over the lower spring perch nipple stamped into the control arm, so no changes were needed on that end. We will make a production version of these Delrin adapters just for the Mk7 GTi / Audi TT Mk3.

This image above shows the stack-up of black Delrin adapter, red Vorshlag ride height adjuster, blue Hyperco spring all in the OEM divorced spring location. Again, we do all of this to maximize inboard wheel room - which is critical. Some other shock suppliers will just punt and send you coilover spring hardware, and on some other car models you can do a coilover rear without eating up wheel room, but this is not one of those cars. For this model MCS inverts the rear shock and puts the rebound knob on the bottom, as shown above.

This makes the rebound knob a lot easier to access - as the OEM upper shock mount makes the top of the shock "blind" and inaccessible. It's a nicely made OEM upper shock mount, a cast aluminum and bolts sideways into the chassis - just like the S550 Mustang.

MOUNTING REMOTES

Remote reservoirs are an added hassle for both mounting the canisters and running & protecting the hoses, but they do have their advantages (additional stroke). The reservoir brackets always seems to take more time than we want to build, but it is very critical. We've seen folks cut corners on this step on their $4400 RR2 shocks - just hose clamping the reservoirs to whatever was nearby.

What usually results is they come loose and hit something, rub through a hose, clamp them too hard and pinch a piston, or worse - the reservoirs FALL OFF and drag on the road to the point that they are ruined. Placement is also important - you need to be able to access the Compression knobs on the canisters, but you need to keep the fluid filled reservoir away from heat sources and road debris and rocks. The rear canisters are mounted vertically behind a plastic splash shield but where you can easily see the face of the knob to see + and - markings.

How these canisters are clamped and held in place is also crucial - grab them in the wrong position on the canisters, and clamp too tightly, and the working piston or floating piston inside can "stick" in the bore.

We make these aluminum cradle clamps and secure them with zip-ties in the grooves machined by MCS, where the pistons are not traveling. These take a bit of work to make and someday I'd like to have a production solution. For now we just make these for in-house installations only.

Lastly the hoses themselves need to be secured. These are stainless braided and rubber covered. If these move relative to something nearby they can literally saw through almost anything - sheet metal, plastic, rubber - but they can also be damaged or cut, which will end your day in a hurry. We secure these hoses with strategically placed P-clamps and check to make sure the hoses don't pull on the clamps during suspension travel and steering rotation. The rears are inverted on this car, so the hoses never move up/down (see above), but the fronts definitely do.

FINAL SETUP STEPS

After you have the shocks and struts installed there is still a bit of work to do. First you need to get the ride heights set. The image below is where we settled on for the Mk3 Audi TT. We measure center of wheel to fender lip, which removes tire height from any calculations.

This is about 1" lower than stock, and what the MCS strut and shock lengths + make droop + total stroke calculations took us to. This should give the best compromise between bump (upwards) and droop (downward) travel of these MCS shocks.

Then we added 175 pounds of ballast in the driver's seat, unhooked the swaybars at both ends, and did a corner balance. This is where we adjust the ride heights at each corner to get the "cross weights" (the LF + RR and RF + LR) to both be equal. On this car we could only get 49.5% / 50.5%, due to the added challenges of the forward engine placement and heavy front weight bias. Sometimes you get limited, but on most cars we can get the cross weights to equal 50/50.

The setup sheet above shows the ride heights/cambers/toe settings it came with + our final adjustments after the corner balance. We also noted the initial shock settings we sent the car out with. Notice the lack of front toe out - this is because this car was driven 4 hours each way to and from our location. For a full tilt autocross setup a little front toe out might help turn in. The 1/4" of rear total toe in also helps turn-in and corner exit without hurting street tire wear.

Evan and Brad from Vorshlag also aligned the car, using a brand new Hunter rack we rent from a nearby shop. We were the first ones to use this rack so they had to figure out all of the software, but it worked great and we got good numbers out of the car.

There were some other little challenges, all of which had to do with this being a used car that the owner had just picked up - but we fixed everything we found. Overall we were very happy with how the MCS install turned out, and so was the owner - who took it a day later to an autocross for testing, and loved it. We will see how he does in STH at Nationals!